Method for producing high quality biodiesel fuel

Abstract

The purpose of the present invention is to provide a method for producing a high quality biodiesel fuel having excellent oxidation stability and few low-temperature deposits. This purpose can be achieved by the following: hydrogenating a biodiesel fuel so as to selectively convert unsaturated fatty acid monoglycerides and then removing fatty acid monoglycerides through precipitation; or using an adsorbent to further remove fatty acid monoglycerides to a high degree from the biodiesel fuel produced using the method mentioned above.

The invention claimed is: 
     
       1. A method for producing a high quality biodiesel fuel, comprising the sequential steps of:
 (a) hydrogenating a biodiesel fuel so as to selectively convert unsaturated fatty acid monoglycerides into readily precipitatable saturated fatty acid monoglycerides; 
 (b) allowing the biodiesel fuel to stand still to precipitate fatty acid monoglycerides; 
 (c) removing the precipitated fatty acid monoglycerides by filtration; and, 
 (d) thereafter removing remaining fatty acid monoglycerides by adsorption with an adsorbent. 
 
     
     
       2. The method of  claim 1 , comprising precipitating the fatty acid monoglycerides in step (b) at a precipitation temperature of 10° C. to 45° C. 
     
     
       3. The method of  claim 1 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, clay minerals, zeolites, diatomaceous earth, magnesium silicates, and alumina. 
     
     
       4. The method of  claim 1 , comprising hydrogenating the biodiesel fuel in step (a) at a hydrogen pressure of 0.2 MPa to 0.7 MPa. 
     
     
       5. The method of  claim 1 , comprising hydrogenating the biodiesel fuel in step (a) a reaction temperature of 80° C. to 130° C. 
     
     
       6. The method of  claim 1 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, activated clay, and diatomaceous earth. 
     
     
       7. The method of  claim 2 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, clay minerals, zeolites, diatomaceous earth, magnesium silicates, and alumina. 
     
     
       8. The method of  claim 2 , comprising hydrogenating the biodiesel fuel in step (a) at a hydrogen pressure of 0.2 MPa to 0.7 MPa. 
     
     
       9. The method of  claim 2 , comprising hydrogenating the biodiesel fuel in step (a) at a reaction temperature of 80° C. to 130° C. 
     
     
       10. The method of  claim 2 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, activated clay, and diatomaceous earth. 
     
     
       11. The method of  claim 3 , comprising hydrogenating the biodiesel fuel in step (a) at a hydrogen pressure of 0.2 MPa to 0.7 MPa. 
     
     
       12. The method of  claim 3 , comprising hydrogenating the biodiesel fuel in step (a) at a reaction temperature of 80° C. to 130° C. 
     
     
       13. The method of  claim 4 , comprising hydrogenating the biodiesel fuel in step (a) at a reaction temperature of 80° C. to 130° C. 
     
     
       14. The method of  claim 4 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, activated clay, and diatomaceous earth. 
     
     
       15. The method of  claim 5 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, activated clay, and diatomaceous earth. 
     
     
       16. The method of  claim 7 , comprising hydrogenating the biodiesel fuel in step (a) at a hydrogen pressure of 0.2 MPa to 0.7 MPa. 
     
     
       17. The method of  claim 8 , comprising hydrogenating the biodiesel fuel in step (a) at a reaction temperature of 80° C. to 130° C. 
     
     
       18. The method of  claim 8 , wherein the adsorbent of step (d) is at least one selected from the group consisting of silica gel, activated clay, and diatomaceous earth. 
     
     
       19. The method of  claim 16 , comprising hydrogenating the biodiesel fuel in step (a) at a reaction temperature of 80° C. to 130° C.